RPGRIP1L and nephronophthisis: These examples include a common polymorphism in the RPGRIP1L gene that is associated with retinal disease across the ciliopathies [Khanna et al., 2009], a common polymorphism in AHI1 that is associated with retinal disease in patients with nephronophthisis [Louie et al., 2010], and a worsened neurological phenotype in patients with a CEP290 mutation together with a heterozygous AHI1 mutation [Coppieters et al., 2010].